This was reported by Andrew Coughlan via email, it did not make it into the bug list.
If all the profiles are deleted (or similarly not actually found) then no sound is generated. The files are by default in /usr/local/share/bristol/memory/profiles.
There is one file that defines some midi table profiles and these were initialised from the MIDI controller map file. If the file did not exist then velocities and frequencies would end up all being zero for every key. Fixed this such that failure to scan the file, or to find it, result in default values being put into the tables.
This will go out with 0.50.2.